change user_name still used as login and add display_name for dashboard view instead of username on login

backend/database/ERD_Dashboard_Chicken_Counting.md

@@ -57,6 +57,7 @@ erDiagram
     USER_ACCESS {
         int user_id PK "NOT NULL"
         varchar user_name "30 NOT NULL"
+        varchar display_name "30 NOT NULL"
         varchar password_hash "255 NOT NULL"
         varchar status "30 NOT NULL"
         timestamp created_at "NOT NULL"

backend/database/erd_schema.sql

@@ -25,10 +25,10 @@
 CREATE TABLE IF NOT EXISTS user_access (
     user_id         SERIAL PRIMARY KEY,
     user_name       VARCHAR(30)  NOT NULL UNIQUE,
+    display_name    VARCHAR(30)  NOT NULL UNIQUE,
     password        VARCHAR(128) NOT NULL,
     last_login      TIMESTAMP WITH TIME ZONE,
     is_superuser    BOOLEAN      NOT NULL DEFAULT FALSE,
-    is_staff        BOOLEAN      NOT NULL DEFAULT FALSE,
     is_active       BOOLEAN      NOT NULL DEFAULT TRUE,
     created_at      TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
     updated_at      TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,